Dengue hemorrhagic fever is caused by: March 2010
**Core Concept**
Dengue hemorrhagic fever (DHF) is a severe form of dengue fever, a mosquito-borne viral disease caused by the dengue virus. The dengue virus is a flavivirus that affects the liver, spleen, and lymph nodes, leading to hemorrhagic manifestations and shock.
**Why the Correct Answer is Right**
Dengue hemorrhagic fever is primarily caused by the dengue virus serotype 2 (DENV-2) and, to a lesser extent, DENV-3. The pathogenesis of DHF involves the viral replication in monocytes and macrophages, leading to the release of pro-inflammatory cytokines and activation of the complement system. This results in plasma leakage, thrombocytopenia, and hemorrhage.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the dengue virus serotype 1 (DENV-1) is more commonly associated with dengue fever than DHF.
**Option B:** Incorrect because there is no established association between DHF and the chikungunya virus.
**Option C:** Incorrect because the yellow fever virus is a different flavivirus that causes a distinct disease entity.
**Clinical Pearl / High-Yield Fact**
Dengue hemorrhagic fever is characterized by a pleomorphic presentation, ranging from mild fever to severe shock and hemorrhage. Early recognition and management are crucial to prevent fatal outcomes.
**Correct Answer:** A. Dengue virus serotype 2 (DENV-2)